Farm background,socioeconomic status,and fertility: The two‐generation hypothesis

Abstract

This paper reports on an examination of whether the effects of farm background on socioeconomic differentials in fertility are diminished among nonfarm couples. The data are for a sample of white ever‐married women belonging to the 1901–1910 birth cohorts. The research provides another test of the two‐generation‐urbanite hypothesis first advanced by Goldberg. Unlike a number of other studies, the findings do not support the hypothesis. Reasons for the lack of support are discussed, and methodological weaknesses of previous studies are identified.     

The exclusive economic zone and antarctica: The dilemmas of non‐sovereign jurisdiction

Abstract

Antarctica is the only continent from which no exclusive economic zones extend. This article examines the EEZ as a legal concept, particularly its relevance for enhancing maritime jurisdiction offshore Antarctica. The study analyzes the political setting in the Antarctic which would affect creation of EEZs in the region, especially the division of the continent into sector claims by certain states and the implications presented by various island groups in the area. An appraisal is made of the legal situation and the jurisdictional opportunities afforded by the Antarctic Treaty System. The author concludes that a recognized political authority, with demonstrated legal competence and capabilities, is administering jurisdictional considerations in the Antarctic area. In its operation, this Antarctic Treaty regime fulfills management and conservation functions analogous to those of EEZs in waters offshore the continent.     

The state,housing policy and Afro‐Caribbean migration to France

France's Afro‐Caribbean population forms a distinctive element in postwar migrant labour recruitment: of French nationality, with an equal balance of men and women, and strongly concentrated in public sector employment, especially in the Paris region. State policy strongly influenced the migration flow from the Caribbean islands, especially from the early 1960s. This article looks at aspects of the migrants’ housing experience, using aggregate statistics to establish general tenure patterns and interviews to recreate biographical histories. Afro‐Caribbean migrants avoided for the most part the worst excesses of the housing crisis of the 1960s and 1970s, though housing conditions ‐ especially for newly‐arriving migrants ‐ were frequently poor. Access to the public housing sector is shown to be crucial, though the role of the state was less direct (specifically aimed at the Caribbean population through the migration agency) than indirect (through the role of employers and the general involvement of the state in housing provision).     

The third United Nations conference on the law of the sea and non‐independent states

Abstract

The Third United Nations Conference on the Law of the Sea is addressing problems that involve all of mankind. Yet there are parts of mankind, non‐independent states and special sovereignties, that are not directly represented at the conference, even though their interests will be directly affected by the decisions taken.

There currently arc around 75 non‐independent states and special sovereignties at different stages of political development and with varying forms of association to a metropolitan power. This can create problems of conflicting jurisdiction over ocean space in two areas particularily: the South Pacific and the Caribbean.

The Conference has attempted”; to deal with the problem of the Law of the Sea and non‐independent states in three ways: by granting observer status to national liberation movements and associated states; through the Transitional Provision; and through the Definitional and Final Clauses. However, a universal formula that would guarantee to these states the resource rights recognized in the proposed Treaty has yet to emerge.     

Estimation of bird distribution based on ring re‐encounters: precision and bias of the division coefficient and its relation to multi‐state models

Capsule The division coefficient is an estimate of the proportion of ringed birds migrating to different destination areas taking into account area‐specific re‐encounter probabilities.

Aims To explore precision and bias of the division coefficient method by a simulation study and to compare the approach with multi‐state models.

Methods In a simulation study true and estimated division coefficients were compared. The division coefficient method was mathematically compared with the multi‐state model.

Results The estimated division coefficients seemed to be unbiased if the assumptions were met. The precision decreased if the bird distribution became similar in both bird groups and when difference between area‐specific re‐encounter probabilities increased. A bootstrap method to assess precision is presented. The estimates from the division coefficient method equal the maximum likelihood estimates in a multi‐state model including only one time interval.

Conclusion Before applying the division coefficient method or a multi‐state model to real data a simulation study should be conducted in order to explore the behaviour of parameter estimation. The division coefficient method with the bootstrap confidence intervals is an easy alternative to a multi‐state model with one time interval when the bird distribution between destination areas (e.g. migratory connectivity) alone is of interest.     

Factors influencing the phytoplankton steady state assemblages in a drinking-water reservoir (Ömerli reservoir, Istanbul)

In situ growth of heterotrophic nanoflagellates (HNF) in Lake Donghu, a eutrophic shallow lake in mainland China, was studied from January 1999 to March 2000 using a modified Weisse protocol. The study results indicated that the growth rates of HNF showed pronounced seasonal variation (–0.37–1.25 d^–1), reaching the maximum during spring to early summer. When the water temperature was higher than 25.5°C, HNF growth was inversely proportional to water temperature. There was an effect by bacterial abundance and autotrophic picoplankton on HNF growth that depended on location. HNF biomass was the highest in late spring, and the HNF production ranged from –2.25 to 35.45 mg l^–1 d^–1 with mean of 3.17 mg l^–1d^–1. When considered in the context of biomass and production data for zooplankton in Lake Donghu, it was evident that HNF contributed significantly to the total zooplankton production in Lake Donghu. These in situ studies indicate that temperature and food supply are the major determinants of HNF abundance and productivity.     

Masting,mixtures and modes: are two models better than one?

A key hypothesis in population ecology is that synchronous and intermittent seed production, known as mast seeding, is driven by the alternating allocation of carbohydrates and mineral nutrients between growth and reproduction in different years, i.e. ‘resource switching’. Such behaviour may ultimately generate bimodal distributions of long‐term flower and seed production, and evidence of these patterns has been taken to support the resource switching hypothesis. Here, we show how a widely‐used statistical test of bimodality applied by many studies in different ecological contexts may fail to reject the null hypothesis that focal probability distributions are unimodal. Using data from five tussock grass species in South Island, New Zealand, we find clear evidence of bimodality only when flowering patterns are analyzed with probabilistic mixture models. Mixture models provide a theory oriented framework for testing hypotheses of mast seeding patterns, enabling the different responses underlying medium‐ and high‐ versus non‐ and low‐flowering years to be modelled more realistically by associating these with distinct probability distributions. Coupling theoretical expectations with more rigorous statistical approaches will empower ecologists to reject null hypotheses more often.     

Trypanosoma cruzi: two genetic groups in Paraná state, Southern Brazil

This paper presents the genetic characterization of Trypanosoma cruzi strains isolated from chronic chagasic patients, triatomines, and sylvatic reservoirs from Paraná state, Southern Brazil, using the RAPD and SSR-PCR techniques. It has shown the presence of both phylogenetic groups of T. cruzi (I and II), describing for the first time the existence of T. cruzi II in Paraná state.     

Evaluation of two visual birdscarers,the Peaceful Pyramid® and an eye‐spot balloon,in two vineyards

Abstract

The effectiveness of a visual birdscarer, the Peaceful Pyramid®, relative to a much‐cheaper eye‐spot balloon was investigated experimentally in two vineyards in Canterbury, New Zealand. Monitoring of bird damage to natural bunches of Riesling grapes within vineyard blocks showed that the rate of starling (Sturnus vulgaris) damage to the crop was reduced significantly by the balloon relative to pyramid and control plots. Nevertheless, after 24 days of monitoring, birds in the balloon plot had damaged 75% of the grapes, respectively (cf. 84% in the pyramid plot). In a second trial, clusters of table grapes were attached to vineyard wire at a Lincoln vineyard. The balloon and pyramid both reduced bird damage to clusters within 15 m of the device, but had no measurable effect on clusters further away. We conclude that neither device would provide growers with any economically significant reduction in grape damage. This study highlights the importance of undertaking quantitative assessments of the numerous bird‐scaring technologies presently available to growers.     

Hidden diversity in the non‐caryophyllaceous plant‐parasitic members of Microbotryum (Pucciniomycotina: Microbotryales)

Abstract

Members of the fungal genus Microbotryum are well‐known parasites on eudicotyledonous plant hosts. However, recent studies focused exclusively on Microbotryum species being parasites in the anthers of Caryophyllaceae in which strong host‐specificity was confirmed by molecular analyses. Consequently, species numbers have risen considerably as multi‐host parasites were split up in so‐called cryptic species. We subjected three non‐caryophyllaceous Microbotryum groups to molecular phylogenetic analyses to see whether we would confirm multi‐host morphospecies or if host‐specific cryptic species in these selected groups could be revealed as well (i.e. a group of non‐caryophyllaceous anther smuts, parasites on different Fallopia species, and parasites on Polygonum bistorta and Polygonum vi‐viparum). We applied a multiple analysis strategy to correct for varying alignment effects on a two‐locus dataset (ITS and LSU rDNA). The results obtained by the different approaches are uniform; high host‐specificity exists in the non‐ caryophyllaceous anther smuts, but overlapping host ranges occur in the parasites of Fallopia species. Results for the parasites of Polygonum are similar, with Microbotryum bistortarum being separated into three lineages and M. marginale forming a lineage on P. bistorta which apparently is conspecific with M. bistortarum p.p. Our study shows that phylogenetic patterns within Microbotryum are much more complicated than deduced from morphological observations alone. Even though Microbotryum species are highly host‐specific, it is impossible to identify species based solely on host taxa affiliation. Species status is reinstated for the anther smut on Salvia pratensis.     

Self‐employment among French‐Canadians: The role of the regional milieu

This article examines the relationship between self‐employment among French‐Canadians and the regional milieu. Our main argument is that self‐employment among French‐Canadians depends on the specific regional milieu. The empirical analysis is based on the public use file on individuals of the 1986 Census of Canada. Self‐employment is related to mother tongue, region, industry, occupation, income and language spoken at home. Then, the association of socio‐economic and socio‐demographic attributes with self‐employment and mother tongue in different French‐Canadian communities is examined. The relation between self‐employment, regional milieus and French‐Canadian communities is further explored using the correspondence analysis method. Results show that in addition to variations in class resources and local opportunities, a majority or minority setting influences the economic niches utilized by French entrepreneurs. Among francophone minorities, small and relatively assimilated communities are usually more entrepreneurial than major francophone concentrations. However, this relationship is not causal, and does not indicate an economic benefit associated with assimilation. Still, French‐Canadians are not a typical entrepreneurial minority that utilizes extensive informal entrepreneurial networks for economic mobility, and the political and economic struggle of French‐Canadians for advancement has not been markedly focused on entrepreneur‐ship. In fact, our results suggest that self‐employment is not a major facet of group mobilization among francophones. Entrepreneurship is perceived by the francophone establishment as an important means for long‐term economic advancement. In attempting to promote entrepreneurship, the need to utilize ethnic networks and community cohesion is greatly acknowledged. We conclude that the preservation of autonomous ethno‐linguistic identity is viewed not only as a means for economic advancement but as a major goal by itself. Hence, French‐Canadians resemble, perhaps, certain sub‐national minorities in Europe, rather than other ethnic minorities in North America. The desired relationship between self‐employment and retention of group identity does not yet prevail, among French‐Canadians, and their political and economic struggle for advancement, so far, has not been focused on entrepreneurship.     

The skeletal function of non‐genic nuclear DNA: new evidence from ancient cell chimaeras

DNA can be divided functionally into three categories: (1) genes — which code for proteins or specify non-messenger RNAs; (2) semons — short specific sequences involved in the replication, segregation, recombination or specific attachments of chromosomes, or chromosome regions (e.g. loops or domains) or selfish genetic elements; (3) secondary DNA — which does not function by means of specific sequences. Probably more than 90% of DNA in the biosphere is secondary DNA present in the nuclei of plants and phytoplankton. The amount of genic DNA is related to the complexity of the organism, whereas the amount of secondary DNA increases proportionally with cell volume, and not with complexity. This correlation is most simply explained by the skeletal DNA hypothesis, according to which nuclear DNA functions as the basic framework for the assembly of the nucleus and the total genomic DNA content functions (together with relatively invariant folding rules) in determining nuclear volumes. Balanced growth during the cell cycle requires the cytonuclear ratio to be basically constant, irrespective of cell volume; thus nuclear volumes, and therefore the overall genome size, have to be evolutionarily adjusted to changing cell volumes for optimal function. Bacteria, mitochondria, chloroplasts and viruses have no nuclear envelope; and the skeletal DNA hypothesis simply explains why secondary DNA is essentially absent from them but present in large cell nuclei. Hitherto it has been difficult to refute the alternative hypothesis that nuclear secondary DNA (whether junk or selfish DNA) accumulates merely by mutation pressure, and that selection for economy is not strong enough to eliminate it, whereas accumulation in mitochondria and plastids is prevented by intracellular replicative competition between their multiple genomes. New data that discriminate clearly between these explanations for secondary DNA come from cryptomonads and chlorarachneans, two groups of algae that originated independently by secondary symbiogenesis (i.e., the merger of two radically different eukaryote cells) several hundred million years ago. In both groups the nucleus and plasma membrane of the former algal symbiont persist as the nucleomorphs and periplastid membrane, respectively. The fact that nucleomorphs have undergone a 200- to 1000-fold reduction in genome size and have virtually no secondary DNA shows that selection against non-functional nuclear DNA is strong enough to eliminate it very efficiently; therefore, the large amounts of secondary DNA in the former host nuclei of these chimaeras, and in nuclei generally, must be being maintained by positive selection. The divergent selection for secondary DNA in the nucleus and against it in nucleomorphs is readily explicable by the skeletal DNA hypothesis, given the different spectrum of gene functions that it encodes.This revised version was published online in October 2005 with corrections to the Cover Date.     

The extravascular compartment of the bone marrow: a niche for Plasmodium falciparum gametocyte maturation?

ABSTRACT: BACKGROUND: Plasmodium falciparum immature gametocytes accumulate in the bone marrow, but their exact location in this tissue remains unclear. METHODS: The stage and deposition pattern of gametocytes was analysed on histological sections of a bone marrow sample collected in a patient with subacute P. falciparum malaria. RESULTS: A majority (89%) of immature stages II to IV gametocytes and a minority (29%) of mature stage V gametocytes were observed in extravascular spaces. Discussion and conclusion These observations represent a valuable step towards understanding sequestration patterns of P. falciparum gametocytes and may ultimately lead to novel transmission-blocking interventions.